Evolutionary Insights on Lockdowns

One aspect of the pandemic that’s received comparatively little attention is the impact that ‘non-pharmaceutical interventions’ have had on pathogens other than SARS-CoV-2.  

All the things we’ve been doing over the past year and a half – lockdowns, voluntary social distancing, frequent use of hand sanitiser – are highly unusual. And they may have reduced our exposure to many different viruses and bacteria.

The potential consequences of this reduced exposure were discussed in an article published in Proceedings of the National Academy of Sciences last November. That article – which represents the combined efforts of a dozen scientists – lists 10 ‘evolutionary insights’ on the COVID-19 pandemic.

The second insight listed is that members of ‘generation quarantine’ may lack critical microbial exposures. As the authors note: “Quarantine has temporarily halted the regular exposure to novel pathogens that is characteristic of human social interaction.”

While most adults have already been exposed to many pathogens at least once, children may not have been. And proper cognitive development, the authors note, “requires adequate and diverse microbial exposure”.

They cite experimental evidence that animals deprived of normal microbiota during critical windows “develop into adults with altered cognition and anxiety”, as well as evidence that disruptions to the microbiome are associated with some neurodegenerative diseases.

Lockdowns and social distancing, the authors note, will result “in a generation whose neurodevelopment will have been influenced disproportionally more by the microbial environment of their natal family in quarantine than by the outside world”. And the long-term effects of this are “unknown”.

This year, New Zealand has already seen an unusually large outbreak of RSV (a respiratory virus affecting children), which doctors have attributed to an ‘immunity debt’ caused by lockdowns last winter. We may have to wait months or years to get a full picture of the impact on children’s health and development.

All 10 of the ‘evolutionary insights’ listed by Benjamin Seitz and colleagues are interesting, and the paper is worth reading in full.